Aging, Physical Activity, and Hormones in Women—A Review

Women experience significant changes in endocrine function during aging. Decreasing levels of anabolic hormones may be associated with musculoskeletal atrophy and decrease in function that is observed in older women and, as a result, there has been an increase in the use of pharmacological hormone therapies. It is difficult to distinguish, however, between physiological changes that are truly age related and those that are associated with lifestyle factors such as physical activity participation. Some research has shown that circulating levels of anabolic hormones such as DHEA(S) and IGF-I in older women are related to physical activity, muscle function, and aerobic power. Exercise-intervention studies have generally shown that increasing age blunts the acute hormonal response to exercise, although this might be explained by a lower exercise intensity in older women. There have been relatively few studies that examine hormonal adaptations to exercise training. Physical activity might have an effect on hormone action as a result of changes in protein carriers and receptors, and future research needs to clarify the effect of age and exercise on these other components of the endocrine system. The value and safety of hormone supplements must be examined, especially when used in combination with an exercise program.

Orthotopic autotransplantation of cryopreserved ovarian tissue to a woman cured of cancer–follicular growth, steroid production and oocyte retrieval

Cryopreservation of human ovarian tissue is now an option for cancer patients facing treatment with gonadotoxic regimes, as a means of preserving their fertility. So far, there have been only a few reports on autotransplantation of frozen-thawed tissue with regard to restoration of ovarian function. The present report describes a 32-year-old woman diagnosed with Hodgkin's lymphoma, who had cryopreserved ovarian tissue transplanted orthotopically after secondary ovarian failure due to chemotherapy. Only 8 weeks after transplantation, ultrasonography of the remaining ovary revealed two follicles with diameters of 10 and 15 mm. Concomitantly, circulating concentrations of oestradiol increased, while concentrations of gonadotrophins decreased. In the following months, the patient menstruated three times. Subsequent pituitary down-regulation with a gonadotrophin-releasing hormone (GnRH) agonist and ovarian stimulation resulted in development of one pre-ovulatory follicle from which a metaphase II oocyte was retrieved; however, this oocyte was unable to sustain further development after intracytoplasmic sperm injection (ICSI). Intrafollicular concentrations of oestradiol and progesterone suggested a normal luteinizing response of the follicle to human chorionic gonadotrophin stimulation. A 7-month follow-up revealed continued vivid follicular activity and normal oestradiol concentrations. In conclusion, cryopreserved human ovarian tissue restored ovarian function for several cycles and sustained development of mature oocytes in a woman cured of cancer.

[Adipose tissue as an endocrine organ: role in pathogenesis of ischemic heart disease and insulin independent diabetes mellitus]

Obesity is a risk factor for cardiovascular morbidity and mortality. The present review of the modern literature is devoted to the problem of regarding the adipose tissue as not only a repository of energy supplies but an active endocrine organ as well whose activity exerts a definite effect on the function of many bodily systems. Specific emphasis is directed toward aspects of the function of certain secretory proteins involved in the process of the arterial pressure regulation and/or organs injuring.

Do regional differences in adipocyte biology provide new pathophysiological insights?

Obesity is an increasing health problem in many countries. Striking differences exist in the magnitude of the impact of different obesities on comorbidities. Individuals with peripheral obesity ('pears') possess fat distributed subcutaneously in gluteofemoral areas and the lower part of the abdomen, and are at little risk of metabolic complications. Conversely, individuals with upper-body obesity ('apples') accumulate fat in subcutaneous and visceral deposits and are more prone to metabolic and cardiovascular problems, particularly when visceral fat deposits are abundant. In this article, whether the different risk factors for obesity of 'apples' and 'pears' are largely related to the heterogeneity of function and responsiveness of the adipocytes from visceral and subcutaneous deposits is questioned. Possible pharmacological approaches to the treatment of obesity and related diseases are also considered.

Glycoprotein hormone GalNAc-4-sulphotransferase

The glycoprotein hormones lutropin (LH) and thyrotropin and a limited number of additional glycoproteins bear carbohydrate structures terminating with the unique sequence SO(4)-4-GalNAcbeta1,4GlcNAcbeta that has been conserved in the glycoprotein hormones of all vertebrate species. Synthesis of these structures is mediated by a protein-specific beta1,4GalNAc-transferase and a GalNAc-4-sulphotransferase (GalNAc-4-ST1). GalNAc-4-ST1 is a member of a family of sulphotransferases that includes HNK-1 sulphotransferase, chondroitin-4-sulphotransferases-1-3 and dermatan-4-sulphotransferase-1. With the exception of HNK-1-ST, these sulphotransferases add sulphate to the C-4 hydroxy group of either terminal or non-terminal beta1,4-linked GalNAc. GalNAc-4-ST1 is most highly expressed in pituitary, cerebellum and other regions of the brain. The terminal GalNAcSO(4) on LH is recognized by the cysteine-rich domain of the mannose/GalNAc-4-SO(4) receptor located in hepatic endothelial cells. Each cysteine-rich domain binds a single terminal GalNAc-4-SO(4), and the receptor must form non-covalently associated homodimers in order to simultaneously engage two GalNAc-4-SO(4) moieties on separate oligosaccharides with sufficient affinity to form stable complexes. The receptor mediates the clearance of LH from the blood. This clearance, in conjunction with the stimulated release of hormone from dense core granules in pituitary gonadotroph cells, is required to produce the episodic rise and fall in LH levels needed for optimal oestrogen production during the implantation of embryos in the uterus.

[Endocrine and metabolic expression in bronchogenic carcinoma]

In the present paper, the authors reviews the endocrine and metabolic manifestations in bronchogenic carcinoma. Disorders as paraneoplastic syndromes (hypercalcemia, syndrome of inappropriate antidiuretic hormone, carcinoid and Cushing's syndromes) and others endocrinopathies are discussed. Hypertrophic pulmonary osteoarthropathy is briefly reviewed.

Identification and localization of eight distinct hormone-producing cell types in the pituitary of male Atlantic halibut (Hippoglossus hippoglossus L.)

The eight distinct hormone-producing cell types in the adenohypophysis of male Atlantic halibut (Hippoglossus hippoglossus L.) were identified and localized using immunohistochemistry and in situ hybridization. Lactotropes either occupied most of the rostral pars distalis (RPD) or they were arranged in follicular structures located along the periphery of the RPD. Corticotropes were confined to a thin layer of RPD cells bordering the pars nervosa (PN). The somatotropes were arranged in multicellular layers bordering the highly convoluted PN penetrating the proximal pars distalis (PPD), while thyrotropes, scattered in small islets in between the somatotropes, were located in the centro-dorsal part of the PPD. Gonadotropes were found throughout the PPD. Immunoreactivity to glycoprotein-alpha and luteinizing hormone beta-subunit was also observed along the periphery of the pars intermedia (PI), indicating that a thin extension of the PPD surrounded the PI. In situ hybridization showed that follicle-stimulating hormone and luteinizing hormone were produced in distinct cells of the PPD. PI contained somatolactotropes bordering the highly convoluted PN, and melanotropes that showed positive immunostaining against both anti-alpha-melanocyte-stimulating hormone and anti-beta-endorphin. The general cellular organization was similar to that of other teleost fish. These results lay the basis for future investigations on Atlantic halibut pituitary physiology.

Administration of insulin-like growth factor I to rhesus monkeys does not augment gonadotropin-stimulated ovarian steroidogenesis

Although it is well established that IGF-I is able to amplify the actions of FSH and LH on ovarian cells in vitro, little information is available regarding the effects of IGF-I on ovarian function in vivo. To address this question, rhesus monkeys whose spontaneous gonadotropin secretion was interrupted with a GnRH antagonist received continuous iv infusions of saline, IGF-I (240 microg/kg.d), or IGF-I (240 microg/kg.d) plus human GH (hGH) (200 microg/kg.d) 7 d before and continuing throughout a 15-d iv infusion of hFSH and hLH during which serum LH concentrations were maintained at 7-10 mIU/ml and FSH concentrations were incrementally increased every 3 d from 7.5 to 17.5 mIU/ml. Serum estradiol concentrations in saline-treated control animals did not differ (P > 0.05) from animals treated with IGF-I + hGH. In contrast, serum estradiol levels in IGF-I-treated animals were significantly less (P < 0.05) than those of control or IGF-I + hGH-treated animals. Serum androstenedione levels did not differ among the three treatment groups. Analysis of follicular fluids on the final day of gonadotropin infusion indicated that intrafollicular IGF-I concentrations paralleled serum IGF-I concentrations in all treatment groups. Measurement of the ratio of IGF-I to IGF-binding protein-3 in follicular fluids indicated that there was not a disproportionate increase in I-binding protein-3 in animals infused with either IGF-I alone or IGF-I + hGH. Concentrations of GH in follicular fluids of IGF-I treated animals were less than control animals suggesting that the diminished responsiveness of ovaries to FSH in the IGF-I treatment group may have been due to reduced GH.

Ca2+-activated, large conductance K+ channel in the ovary: identification, characterization, and functional involvement in steroidogenesis

Progesterone production by the corpus luteum is a process vital for reproduction. In humans its secretion is stimulated by the placental hormone human chorionic gonadotropin (hCG), and this stimulatory action can also be observed in cultured human luteinized granulosa cells (GCs). We now provide evidence that opening of a Ca(2+)-activated K(+) channel, the BK(Ca), is crucially involved in this process. Immunohistochemistry and RT-PCR revealed the presence of the pore-forming alpha-subunit in human luteinized GCs and in luteal cells of human, macaque, and rat, implying that BK(Ca) channels are important throughout species. Blocking of BK(Ca) channels by iberiotoxin attenuated hCG-induced progesterone secretion. The inhibitory action of iberiotoxin suggests that BK(Ca) channels are activated in the course of hCG-induced steroidogenesis. In search of physiological activators we used an electrophysiological approach and could preclude a direct regulation of channel activity by hCG or GC-derived steroids (progesterone and 17beta-estradiol). Instead, the peptide hormone oxytocin and an acetylcholine (ACh) agonist, carbachol, evoked transient BK(Ca) currents and membrane hyperpolarization. These two molecules are both secreted by GCs and act via raised intracellular Ca(2+) levels. The release of oxytocin is stimulated by hCG, and a similar mechanism is likely in the case of ACh. We conclude that BK(Ca) channel activity in GCs is mediated by components of the intraovarian signaling system, thereby interlinking a systemic hormonal and a local neuroendocrine system in control of steroidogenesis.

Regulation of steroid hormone biosynthesis in R2C and MA-10 Leydig tumor cells: role of the cholesterol transfer proteins StAR and PBR

The MA-10 mouse Leydig tumor cell line produces large amounts of steroids only in response to hormonal stimulation while the R2C rat Leydig tumor cell line is constitutively steroidogenic in nature. In an effort to uncover the potential reasons for constitutive steroidogenesis in R2C cells, we have recently shown that compared to MA-10 cells, R2C cells express much higher levels of the Scavenger Receptor Class B type 1 which results in a higher capacity for cholesteryl ester uptake through the selective uptake pathway. We also found an enhanced expression of Hormone Sensitive Lipase and the Steroidogenic Acute Regulatory protein in these cells and reasoned that they may further facilitate the conversion of cholesteryl esters to free cholesterol and its mobilization to the inner mitochondrial membrane, thus rendering them constitutively steroidogenic. Given the proposed role of the peripheral-type benzodiazepine receptor (PBR) in conferring a constitutively steroidogenic phenotype to the R2C cells, the current study was conducted to investigate the relationship between its expression in MA-10 and R2C cells and correlate it with the constitutive nature of R2C cell steroidogenesis. Our studies show that PBR expression as measured by PK 11195 ligand binding and Western analysis is much higher in MA-10 cells than R2C cells. We also determined that the affinity of ligand binding to the PBR is comparable in the two cell lines, suggesting that PBR is unlikely to be solely responsible for the constitutive nature of R2C cell steroidogenesis.

Hormones and human trophoblast differentiation: a review

In the human, fetal cytotrophoblastic cells play a key role in the implantation process and in placental development. With the progression of placentation, two pathways of differentiation lead to the formation of two distinct phenotypes. In the villous trophoblast (fusion phenotype), the trophblast differentiates from the fusion of mononuclear cytotrophoblastic cells into a syncytium, the syncytiotrophoblast. Bathing the maternal blood, the syncytiotrophoblast is involved in maternal-fetal exchanges and in placental endocrine functions. In the extravillous trophoblast (proliferative/invasive phenotype), the cytotrophoblastic cells proliferate and migrate into the decidua, remodeling the pregnant endometrium and its vasculature. This review summarizes our current knowledge of the key step of villous differentiation-the cell-cell fusion of the cytotrophoblastic cells--and on the invasion process of extravillous trophoblast. Experimental evidence demonstrates that the genetic differentiation/invasion programs of cytotrophoblastic cells could be modulated by their environment: oxygen, extracellular matrix, and soluble factors (cytokines, growth factors, and hormones). Cytotrophoblastic cells fusion and the functional differentiation of villous trophoblast are specifically stimulated by estradiol, glucocorticoids, and human chorionic gonadotropin (hCG) whereas progesterone is ineffective. Because these hormones are temporally secreted in large amounts and present at the fetomaternal interface, they are in good position to play a physiologic role in trophoblast differentiation. hCG may be important very early in pregnancy, when production of this glycoprotein is maximal, whereas estrogen increasingly produced by the fetoplacental unit and cortisol secreted from the fetal adrenal may be implicated in the end-stage maturation and aging of the trophoblast.

Reproductive disturbances, pituitary lactotrope adenomas, and mammary gland tumors in transgenic female mice producing high levels of human chorionic gonadotropin

To assess the consequences of prolonged exposure to elevated levels of LH/human chorionic gonadotropin (hCG) in the female, we developed a transgenic (TG) mouse model (hCGbeta+) that overexpresses the hCGbeta-subunit cDNA. Because of the promoter used, ubiquitin C, the transgene is expressed in multiple tissues, including the pituitary gland, in which coupling with the endogenous common alpha-subunit results in synthesis of high levels of bioactive hCG. The TG females presented with precocious puberty, infertility, enhanced ovarian steroidogenesis, and abnormal uterine structure. Pituitary enlargement was evident from the age of 2 months, which progressed to adenomas by the age of 10-12 months. Immunohistochemical studies and electron microscopy demonstrated lactotrope origin for the adenomas, associated with severe hyperprolactinemia. The mammary glands of TG females showed marked lobuloalveolar development followed by mammary tumors with characteristics of adenocarcinoma at the age of 9-12 months. More than 90% of penetrance and high frequency of metastasis (47%) was observed. Formation of the pituitary and mammary gland tumors was totally abolished by ovariectomy despite persistently elevated hCG levels. Taken together, these findings suggest that the hCG-induced aberrations of ovarian function are clearly responsible for the extragonadal tumors observed in these TG mice.

Artificial mammalian gene regulation networks-novel approaches for gene therapy and bioengineering

Recently developed strategies for targeted molecular interventions in mammalian cells have created novel opportunities in biotechnological and biomedical research with huge economic and therapeutic impact: the design of mammalian cells with desired phenotypes for biopharmaceutical manufacturing, tissue engineering and gene therapy. These advances have been enabled by constructing artificial gene regulation systems with control modalities similar to those evolved in key regulatory networks of mammalian cells. This review highlights recurring cellular regulation strategies and artificial gene regulation technology currently in use for rational reprogramming of cellular key events including metabolism, growth, differentiation and cell death to achieve sophisticated bioprocess and therapeutic goals.

Modulation of folliculogenesis and steroidogenesis in women by graded menotrophin administration

BACKGROUND

To test the effects of progressively decreasing dosages of exogenous LH we combined various amounts of HMG, containing FSH, LH and HCG, and highly purified (HP) FSH to treat 120 GnRH agonist-suppressed infertile female patients as candidates for controlled ovarian stimulation (COS).

METHODS

Subjects were randomly assigned to four treatment groups that received the following daily i.m. gonadotrophin regimens: A, FSH 150 IU only; B, FSH 150 IU and LH activity 37.5 IU; C, FSH 150 IU and LH activity 75 IU; D, FSH 150 IU and LH activity 150 IU. FSH dose adjustments were allowed only after the 14th treatment day. Monitoring included transvaginal ultrasound at 2-day intervals and daily determinations of LH, FSH, estradiol (E(2)), progesterone, testosterone and HCG.

RESULTS

Duration of COS was significantly shortened in patients receiving at least 75 IU daily of LH activity. Small (<10 mm diameter) pre-ovulatory ovarian follicle occurrence was inversely correlated with LH activity dose administered (r = -0.648, P < 0.0001) and serum HCG levels (r = -0.272, P < 0.01) but not to serum LH levels. Serum testosterone levels were positively correlated to the LH activity dose administered (r = 0.313, P < 0.001), while serum progesterone levels were positively correlated to the FSH dose administered (r = 0.447, P < 0.00001) but not to the LH activity dose administered.

CONCLUSIONS

Firstly, HCG content considerably contributes to HMG activity; secondly, menotrophin LH activity content can reduce in a dose-dependent manner the occurrence of small pre-ovulatory follicles; and finally, contrary to common belief, enhanced FSH stimulation rather than LH activity appears to cause premature follicle luteinization during COS.

Characterization of a repressor element in the promoter region of proprotein convertase 2 (PC2) gene

The proprotein convertase PC2 is primarily expressed in neuroendocrine cells where it mediates the proteolytic maturation of prohormones and proneuropeptides. We have identified in the upstream sequence of its gene a conserved domain partially homologous to the repressor element RE1/NRSE found in several genes for neuronal proteins. RE1/NRSE binds the silencing transcription factor REST/NRSF, a nuclear protein primarily found in nonneuronal cells. To determine the functionality of the PC2 gene RE1-like sequence (RE1-lk), we examined by electrophoretic mobility shift assays its ability to attach nuclear factors from PC2-expressing and nonexpressing cells. Specific binding factors were mostly detectable in PC2-non-expressing cells. These factors differ from REST/NRSF, as molar excess of competing RE1/NRSE could not prevent their binding to RE1-lk. Reciprocally, molar excess of RE1-lk could not prevent the binding of RE1/NRSE to the DNA-binding domain of a recombinant REST/NRSF. The presence of RE1-lk in cis reduced the ability of the PC2 promoter and the heterologous phosphoglycerate kinase promoter to drive expression of a green fluorescent protein reporter gene in transiently transfected PC2-nonexpressing cells, but not in PC2-expressing cells. These observations suggest that binding of transcription-silencing factors to the RE1-lk element may contribute to repression of the PC2 gene in nonneuroendocrine cells.

Steroid receptor coactivator-1 deficiency causes variable alterations in the modulation of T(3)-regulated transcription of genes in vivo

Thyroid hormone exerts its biological effect by binding to a TR. Both liganded and unliganded TRs regulate the transcription of T(3)-responsive genes. Cofactors with activating or repressing function modulate the transcriptional regulation by TRs. We showed that steroid receptor coactivator 1 (SRC-1)-deficient mice (SRC-1(-/-)) exhibit partial resistance to thyroid hormone at the level of the pituitary thyrotrophs. To determine whether SRC-1 deficiency affects globally T(3)-dependent transcriptional regulation, we studied the effects of thyroid hormone deprivation and replacement on the expression of several genes in different tissues of SRC-1(-/-) and wild-type mice (SRC-1(+/+)). Thyroid hormone deficiency was induced by a low iodine diet (LoI) supplemented with propylthiouracil (PTU) for 2 wk. L-T(3) was injected ip for the last 4 d in one group (PTU+T(3) group), and another group (PTU group) received only vehicle. Levels of mRNAs for T(3)-responsive genes were determined by Northern blotting: GH and TSH beta in pituitary; type 1 iodothyronine 5'-deiodinase, spot 14 (S14), and malic enzyme in liver; and sarcoplasmic reticulum calcium adenosine triphosphatase 2 and myosin heavy chain alpha and beta in heart. Serum parameters, TSH, total cholesterol, creatine kinase, and alkaline phosphatase (AP), were also measured. Hypothyroidism produced a comparable increase in TSH beta mRNA in both genotypes, but its suppression by L-T(3) was attenuated in SRC-1(-/-) mice. In contrast, hypothyroidism failed to reduce S14 mRNA levels in SRC-1(-/-) mice. As a consequence, the response to L-T(3) was not observed in these mice. SRC-1 deficiency had no effect on the expression of the rest of the T(3)-responsive genes examined. Of the four serum parameters, the T(3)-mediated decrease in TSH and changes in AP were attenuated in SRC-1(-/-) mice. We conclude that SRC-1 deficiency altered the expression of only some of the T(3)-responsive genes. SRC-1 appears to be involved not only in transcriptional activation by liganded TRs, but also in the suppression by liganded or unliganded TRs. Some of the effects of SRC-1 may be TR isoform specific.

Stanniocalcin 1 (STC1) protein and mRNA are developmentally regulated during embryonic mouse osteogenesis: the potential of stc1 as an autocrine/paracrine factor for osteoblast development and bone formation

STC1, a mammalian homologue of stanniocalcin (STC) which plays a major role in calcium/phosphate homeostasis in fish, has been recently isolated. We have characterized the spatiotemporal distribution of STC1 mRNA and protein during mouse embryonic development generally and osteogenesis specifically. Northern blotting analysis of whole embryos showed that STC1 mRNA is highly and differentially expressed during embryogenesis. By in situ hybridization, STC1 mRNA was detected early in mesenchymal condensations and was then found to be highly expressed in perichondrial cells, periosteal cells, and then osteoblasts during endochondral bone formation. In bones forming by intramembranous ossification, STC1 mRNA was not detected until osteogenic cells appeared. The cellular distribution of STC1 protein closely corresponded to that of its mRNA, but the protein was also detected in hypertrophic chondrocytes. In the MC3T3-E1 osteogenic cell model, STC1 protein and mRNA were detectable throughout proliferation and differentiation stages but levels were relatively higher late during nodule formation/mineralization phases. For comparison, STC1 mRNA was also found in epithelial cells of both embryonic and adult intestine that had not previously been described among tissues responsive to calcium/phosphate transport. These results suggest that STC1 is expressed in a time- and cell-specific manner and may play an autocrine/paracrine role during osteoblast development and bone formation.

Ovarian and adrenal steroid production: regulatory role of LH/HCG

BACKGROUND

The contribution of the adrenal glands to the total circulating steroid pool in women is not well known. There is evidence that human adrenals express the LH receptor gene and that LH may affect adrenal androgen secretion.

METHODS

HCG stimulation tests (a single dose of 5000 IU i.m.) were performed in women at reproductive age (group 1, n = 6, age 21--39 years) before and after treatment with a GnRH agonist for 3 weeks, and in oophorectomized post-menopausal women (group 2, n = 6, 47--59 years) during and after estrogen replacement therapy (ERT).

RESULTS

HCG did not stimulate the secretion of cortisol, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEAS) in group 2. In contrast, in group 1, the basal concentrations of serum 17-hydroxyprogesterone (17-OHP), androstenedione, testosterone and estradiol (E(2)) were stimulated significantly (17-OHP 105%, androstenedione 31%, testosterone 20%, E(2) 136%) by HCG, and the treatment with GnRH agonist decreased the responses. The basal serum concentrations of these steroids were significantly lower in oophorectomized women (17-OHP 57%, androstenedione 46%, testosterone 25%), and HCG did not increase these levels. It can be approximated that the ovarian contribution to the circulating levels of 17-OHP, androstenedione and testosterone is 25--30%, and that the adrenals are the primary source of cortisol, DHEA and DHEAS.

CONCLUSION

LH/HCG does not have a major role in the regulation of adrenal steroid synthesis in endocrinologically healthy women.

Overexpression of human stanniocalcin affects growth and reproduction in transgenic mice

In mammals stanniocalcin (STC) is widely expressed, and in the kidney and gut it regulates serum calcium levels by promoting phosphate reabsorption. To shed further light on its functional significance in mammals we have created several lines of mice that express a human STC (hSTC) transgene. Three lines expressed the hSTC transgene, but only two lines exhibited high expression and contained circulating hSTC, and in these animals there was a reduction in postnatal growth (30-50%) that persisted after weaning. Moreover, even wild-type pups exhibited a growth retardation phenotype when nursed by a transgenic foster mother, and this implies that hSTC overexpression deleteriously affects maternal behavior and/or lactation. The reproductive potential of female transgenic mice was also compromised, as evidenced by significantly smaller litter sizes, but transgenic male fertility was unchanged even though the transgene was most highly expressed in testes. Interestingly, transgene-derived serum hSTC increased significantly after puberty and was severalfold higher in females than in males, suggesting a gender-specific mechanism for maintaining elevated circulating levels of STC. Blood analysis revealed that both transgenic lines had elevated phosphate and decreased alkaline phosphatase levels, indicative of altered kidney and bone metabolism. These studies provide the first evidence that STC is involved in growth and reproduction and reaffirm its role in mineral homeostasis.

Acute and chronic effects of genistein, tyrphostin and lavendustin A on steroid synthesis in luteinized human granulosa cells

BACKGROUND

Phytoestrogens, including genistein and other inhibitors of tyrosine kinases (TKs), inhibit specific steroidogenic enzymes. This study was designed to compare the effects of genistein, with two other TK inhibitors, on steroid synthesis in human granulosa luteal (GL) cells and to identify which steroidogenic enzymes they may affect.

METHODS

GL cells, obtained from women undergoing IVF procedures, were cultured for various periods of time with and without substrates for progesterone and estradiol synthesis, in the presence or absence of the TK inhibitors.

RESULTS

The TK inhibitors significantly suppressed progesterone and estradiol synthesis in a dose-dependent manner over a 48 h culture period. Progesterone production in the presence of 10(-7) mol/l pregnenolone during a 4 h period was inhibited by both acute (4 h) and chronic (24 h) exposure of GL cells to 50 micromol/l genistein (P < 0.05) whilst no significant effects of 50 micromol/l tyrphostin A23 were observed. Genistein (4 and 24 h exposure) inhibited the production of estradiol using 10(-7) mol/l estrone as a substrate, but inhibition of estradiol synthesis using androstenedione or testosterone as substrates was only observed after a 24 h exposure. In contrast, tyrphostin acutely stimulated estradiol synthesis when androstenedione and testosterone were used as substrates (P < 0.05) but not estrone.

CONCLUSIONS

Genistein directly inhibits 3 and 17beta-hydroxysteroid dehydrogenase activity, whilst tyrphostin has an acute stimulatory effect on aromatase activity. Over a longer time (24 and/or 48 h period), both TK inhibitors suppress steroid synthesis.

Functional studies of subcutaneous ovarian transplants in non-human primates: steroidogenesis, endometrial development, ovulation, menstrual patterns and gamete morphology

BACKGROUND

The study objective was to determine if ovarian function would be restored following fresh and cryopreserved extrapelvic autologous ovarian transplantation and if vascular endothelial growth factor (VEGF) administration would augment the success rate.

METHODS

Sixteen regularly cycling female cynomolgus monkeys underwent bilateral oophorectomy and were randomly assigned to one of three treatment groups: (i) sham transplant group (n = 5) underwent transplantation of pieces of adipose tissue; (ii) fresh autologous ovarian transplantation without VEGF administration (n = 6) and (iii) fresh autologous ovarian transplantation with 1 microg of VEGF (n = 5) administered at the transplantation site daily for 14 days after transplantation. The ovarian tissue from the sham transplanted group was cryopreserved. This material was later thawed and transplanted in four out of five of the sham operated group.

RESULTS

Five out of six (83%) of the primates in our transplantation group without VEGF had functioning ovarian transplants while two of five (40%) primates in our transplantation group with VEGF administration had functioning ovarian transplants. The cryopreserved group had two of four primates (50%) with functioning transplants. Ovarian stimulation yielded multiple follicles and one metaphase II oocyte from the fresh and one metaphase II oocyte from the cryopreserved group.

CONCLUSIONS

The success of ovarian transplantation in these non-human primates with menstrual cycles bodes well for the development of ovarian transplantation protocols for women at risk of ovarian failure.